This invention relates generally to the valve actuation field and, more specifically, to an improved method of controlling an electromagnetic valve actuator for an engine of a vehicle.
In a conventional engine of a typical vehicle, a valve is actuated from a closed position against a valve seat to an open position at a distance from the valve seat to selectively pass a fluid, such as a fuel and air mixture, into or out of a combustion chamber. Over the years, several advancements in valve actuations, such as variable valve timing, have improved power output, fuel efficiency, and exhaust emissions. Variable valve timing is the method of actively adjusting either the duration of the close or open cycle, or the timing of the close or open cycle of the valve. Several automotive manufacturers, including Honda and Ferrari, currently use mechanical devices to provide variable valve timing in their engines.
A more recent development in the field of variable valve timing is the use of two solenoid coils located on either side of an armature to open and close the valve heads. Activation of one of the solenoid coils creates an electromagnetic pull on the armature, which moves the valve in one direction. Activation of the other solenoid coil creates an electromagnetic pull on the armature, which moves the valve in the other direction. This system, also known as electromagnetic valve actuator (or xe2x80x9cEMVAxe2x80x9d), allows for an infinite variability for the duration and timing of the open and close cycles, which promises even further improvements in power output, fuel efficiency, and exhaust emissions.
In an engine, it is desirable to swiftly move the valve between the open position and the closed position and to xe2x80x9csoftly seatxe2x80x9d the valve against the valve seat. The force created by the EMVA, which is related to the distance between the solenoid coil and the armature, increases non-linearly as the armature approaches the solenoid coil. In fact, the solenoid coil can forcefully slam the armature against the solenoid coil, which may also forcefully slam the valve head into the valve seat. The slamming of the valve against the valve seat, or the slamming of the armature against the solenoid coils, causes undesirable noise, vibration, and harshness (xe2x80x9cNVHxe2x80x9d) within the vehicle. Thus, there is a need in the automotive industry to create an EMVA with soft seating capabilities.